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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> back box with no back https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1285001057 Message started by CWatters on Sep 20^th, 2010, 5:44pm

Title: back box with no back
Post by CWatters on Sep 20^th, 2010, 5:44pm

I've got a bunch of TV and audio leads to run through a wall with face plates and connectors either side. The boxes I have have have four punch outs but it would be so much easier if the whole back of the box was removed. Before I get the hacksaw out is there such a thing a a back box without a back?

Title: Re: back box with no back
Post by Lectrician on Sep 20^th, 2010, 7:04pm

Kind of - they are known as extenders, extension boxes, extension rings.

They are available in plastic and metal. Commonly used in commercial installs where you use trunking above suspended ceilings and drop 20mm conduit down the partition walls. The 25 or even 35mm backbox needs to sit further back to allow for the conduit adaptor to clear the plasterboard, so extenders are used to take up the difference.

Something like this from Greenbrook. Most wholesalers stock or can get greenbrook stuff, or indeed an equiv.

http://www.greenbrook.co.uk/products.php?nav=176&cat=187&pg=2

Title: Re: back box with no back
Post by CWatters on Sep 20^th, 2010, 11:34pm

Something like that will be perfect. I'll drop in the local electrical supplies place and see if they have any.

Thanks!

Title: Re: back box with no back
Post by CWatters on Sep 22^nd, 2010, 7:42am

First place I tried had some.

Next job will be to make up the faceplates. Need to drill a load of 24mm diameter holes to take Neutrik connectors. Last time that was hard work as plates we have are made from some steel that's more like iron than mild.

Title: Re: back box with no back
Post by sparkydude on Sep 28^th, 2010, 6:24am

Try looking into the q-max sheet metal punches, you drill an 8mm hole and then insert the tool on either side and tighten up forcing the punch through the plate leaving you with a perfect burr free hole.

They come in loads of different sizes.

Nick

Title: Re: back box with no back
Post by CWatters on Sep 28^th, 2010, 8:10am

Thanks. I'll give them a go. One problem is that I need to cut 24mm diameter holes pretty close together so quite worried about the metal between the holes distorting. Might try punching alternate holes and drilling and hand filing the ones in between.

Title: Re: back box with no back
Post by CWatters on Oct 3^rd, 2010, 11:08am

Those punches worked out ok. This is the resulting faceplate...

[gallery fullsize]CWatters/1286099709.jpg[/gallery]

Top row has four HDMI sockets, bottom row has two Speakon sockets, a Network port, an F series/aerial and a 3mm jack for an IR extender.

The HDMI and network connectors are "through" type (eg they have a matching socket on the back) so premade cables can be used both sides.

Hard part was getting everything lined up. Didn't quite manage a perfect job despite printing the layout onto a sticky label. One problem with the punch is they only have small flats on the "nut" part. It tended to pull out of the vice while trying to put max effort into turning the allen key. Had no problems punching holes close together and much easier than drilling and filing out.

[edit]Fullsized the piccy for clarity[/edit]

Title: Re: back box with no back
Post by LS on Oct 3^rd, 2010, 11:00pm

Nice work. Presumably the plate is to match existing style or is it just a soft material that was suitable for adapting?

Title: Re: back box with no back
Post by CWatters on Oct 5^th, 2010, 3:06pm

Yes it's to match existing plates from

http://www.jim-lawrence.co.uk/

Unfortunately rather expensive.

Title: Re: back box with no back
Post by Lectrician on Oct 5^th, 2010, 5:23pm

CWatters wrote on Oct 5^th, 2010, 3:06pm:

Unfortunately rather expensive.

Your not wrong!